Fabrication of GaAs MISFET with nm-thin oxidized layer formed by UV and ozone process

Abstract

Abstract-A gate insulating layer with single nm-order thickness for suppressing gate leakage current is one of the key factors in extending downsizing limits, based upon the scaling rule, of field-effect-type transistors. We describe the fabrication and characterization of GaAs MISFETs with a nm-thin oxidized layer as the gate insulating layer, which is formed by an ultraviolet (UV) and ozone process. The UV and ozone process forms oxidized GaAs layers near the surface, which effectively suppress the reverse leakage current by several orders of magnitude. The fabricated GaAs MISFET can operate not only in the depletion mode, but also in the accumulation mode up to 3 V of the gate voltage for 8-nm-thick oxidized layer due to the current blocking effect of the oxidized layer. A current cutoff frequency of 6 GHz and a maximum oscillation frequency of 8 GHz are obtained for a GaAs MISFET with a 1-m-long gate length and 8-nm-thick oxidized layer.Index Terms-Compound semiconductors, GaAs, MISFET, selfalign, ultraviolet (UV) and ozone process.

GaAs-MISFETs With Insulating Gate Films Formed by Direct Oxidation and by Oxinitridation of Recessed GaAs Surfaces

“…The gate bias was changed from to V in 0.5 V steps. In the (a) 4-0h sample , the pinchoff is not good and a slight decrease in the transconductance is observed around the flatband voltage, similar to the GaAs MOSFETs, which we reported in 2002 [8], implying the existence of interface states. However, in the (b) 4-2h sample, the pinchoff is improved and a higher transconductance is realized.…”

“…We have demonstrated GaAs-MISFETs with an oxinitrided gate insulating layer formed by a combination of UV and ozone oxidation process and a N plasma nitridation process in order to solve the problems associated with GaAs-MOSFETs reported in [8]. The oxinitrided gate device (GaAs-MISFET) exhibited smaller leakage current than the simple oxide gate device.…”

“…The thickness of this layer is proportional to square root of the process period. We also reported that GaAs-MOSFETs and InAlAs/InGaAs-MOSHEMTs with such oxide layers could be operated even beyond their flatband voltage [6]- [8], although dips in transconductance and the hysteresis were apparent in their current-voltage (I-V) curves. In order to overcome these problems, we studied the effect of nitridation upon bare and oxidized GaAs wafers from the points of view of the crystallographic structure near the interface and the electrical and photoluminescence performance.…”

n‐Channel p‐channel enhancement/inversion mode GaAs‐MISFETs with gate insulating layers formed by dry oxi‐nitridation

“…Near the flat band voltage of V g = 1 V, the transconductance is degraded in the region of high drain voltages. Such irregular behavior is confirmed in the n-channel depressiontype MOSFET with an insulating film formed only by oxidation [6,11]. Also, the shift of the pinch-off voltage in the positive direction by nitriding is caused by disappearance of the excess positive charge near the oxidation-only interface when nitriding is applied.…”

Selective Oxidation on High-Indium-Content InAlAs/InGaAs Metamorphic High-Electron-Mobility Transistors

“…Up to now, many efforts have been continuously channeled toward the development of oxidation techniques on the III-V compounds for GaAs-based device application, which include thermal oxidation [1][2][3][4][5][6][7], chemical anodization [8][9][10][11][12], photochemical oxidation [13][14][15][16], plasma oxidation [17][18][19][20], Ga 2 O 3 grown by molecular beam epitaxy (MBE) [21][22][23], Al 2 O 3 grown by atomic layer deposition (ALD) [24], oxidized GaAs or InAlAs prepared by ultraviolet and ozone [25][26][27], and so on. Although the electrical quality of the GaAs-based MOS structures demonstrated to date is not as good as those obtained from the more mature SiO 2 /Si system, some of them have yielded promising results for electronic and optoelectronic applications.…”